PT99308A - PROCESS FOR THE PRODUCTION OF INSTANT CAFE INSTANT IN PO - Google Patents

Abstract

The process consists essentially in removing the undesirable constituents as soon as they are manufactured by carrying out a flash-type evaporation on an extract, whose temperature is above 150 DEG C, produced by the hottest cells, then in reintroducing this extract into the extraction circuit. A second flash-type evaporation is then carried out, separated from the first one by at least one extraction cell, the product of this second operation being reintroduced into the extraction circuit. Application to the production of a powdered soluble instant coffee. <IMAGE>

Description

Description of the patent application of SOCIÉTÉ DES PRODUITS NESTLÉ S, Switzerland, industrial and commercial, based in Vevey, Switzerland, (inventor- Klaus Schlecht, resident in Switzerland) for &quot; PROCESS FOR THE PRODUCTION OF SOLUBLE INSTANT COFFEE IN PÔ &quot; The present invention relates to a process for the production of powdered instant coffee, powdered coffee is classically produced by lyophilization or atomization after evaporation of a coffee extract obtained by filtration of a liquid (Sivetz - Coffee Processing Technology - Volume 1 - Pages 262, 263 - AVI - 1963). The extraction is carried out in countercurrent, that is, the water, under pressure, the a temperature which may be in the range of 100Â ° C to 180Â ° C is introduced into the cell containing the amount of ground roasted coffee which has been further weakened, N extractions having been subjected thereto to the liquid extract of this extraction cell is then washed through the extraction cell containing the amount of coffee that has been used (N-1) times, which follows until the liquid extract passes through the cell that has just been filled with fresh ground toasted coffee. 1

The final extract leaves the latter cell at a temperature in the range of 100,

Thus, the weakened coffee is subjected to the highest temperature while the fresh coffee is subjected to the lowest temperature.

Classically, the hot cells, which contain the weakened coffee, are classically classified as cold cells, which contain the least weakened coffee.

At the end of each extraction cycle the cell containing the weakened coffee is emptied, filled with fresh coffee and, after releasing the cells back together, a new extraction cycle begins. It is known that the higher the extraction temperature the higher the yield. On the other hand, the use of an elevated temperature gives rise to hydrolysis phenomena which give rise to unpleasant organoleptic compounds.

Thus, the extract produced in the hot cells is classically loaded with compounds which, if present in the final extract, then give rise to the production of a powder-soluble coffee which, after being redissolved in hot water, has a marked hydrolysis and caramel taste.

Thus, for example, in US Pat. No. 4,129,665, the extraction of coffee partially evaporates the extract produced in the hot cells before being reintroduced into the cold cells, the extract being evaporated at a temperature in excess of 12Â ° C, More particularly, the evaporation is carried out with the aid of an evaporator. holder consisting of a pressure reducing device * followed by an instantaneous evaporator. 9 2

On the other hand, according to the process of the present invention, at least an amount of extraction liquid identical to that which has been evaporated is added to the extract which has been subjected to evaporation.

According to the process of the present invention, an improvement of the final product is clearly obtained since the hydrolysis and caramel taste buds are clearly decreased.

However, in return for this result, a concomitant decrease in the strength of the desired organoleptic compounds arises, the latter being the more marked the more the treated coffee is less roasted.

One way of avoiding this drawback may be to reduce the effect of the process by increasing the temperature of the instant evaporation, but also thereby obtaining a less good elimination of the compounds to be suppressed. The object of the process according to the invention is therefore to allow the elimination of the organoleptically harmful compounds, without achieving a concomitant reduction of the taste.

In addition, in the above case, even after a filtration phase of the final extract which tends to eliminate the solid particles of the suspended coffee which may arise, there are also suspended solids, such as polysaccharides or proteins, which must be eliminated in order to allow, after evaporation and lyophilization or atomisation of this extract, to obtain a perfectly soluble coffee powder and not causing the appearance of solids in the cup.

These suspended solids are classically removed by centrifugation, the slurry being then decanted, the decantation liquid remaining 3

to the surface reintroduced in the final filtered extract, while the solid residue obtained is eliminated.

This process has as main drawback the generation of a sludge which has to be treated again by decantation and therefore the manipulation is not facilitated.

In addition, centrifugation does not always allow satisfactory disposal of suspended matter.

A further object according to the invention is therefore to provide a process of the kind described above which further reduces the non-soluble fraction present in the final extract. The present invention thus provides a process for producing a soluble instant powdered coffee, whereby an extraction liquid is countercurrently filtered through cells filled with ground roasted coffee, the final extract being then processed into powder, and in which an extract produced by one or more hot cells at a temperature above 150 ° C is subjected to a first flash-off of the instantaneous type, the extract being then reintroduced into the extraction circuit to be subjected to a second evaporation of the instantaneous type separated from the preceding by at least one intermediate extraction cell, the product of this evaporation being then reintroduced into the cold cells of the extraction circuit.

Another object of the present invention is a process of the above-described type according to which extraction liquid is added after the second evaporation and prior to reintroduction into the cold cells. 4

Further advantages are illustrated in more detail in the following description, with reference to the accompanying single figure, given solely by way of non-limiting example and representing a device for carrying out the process according to the invention, the process according to the present invention consists essentially in the elimination of the undesirable constituents immediately after their manufacture, by effecting instantaneous evaporation on an extract, the temperature of which is higher than 150 ° C, produced by the hottest cells, and then in the reintroduction of this extract in the extraction circuit.

A second evaporation of the instantaneous type is then carried out, separated from the preceding by at least one extraction cell, the product of this second operation being reintroduced into the extraction circuit. The first evaporation is preferably carried out at a very low temperature so as to obtain a maximum effect, the second evaporation is carried out at a higher temperature so as to eliminate the last undesirable compounds, further avoiding a loss of the organoleptically desired elements.

Thus, preferably, the first evaporation is carried out at 60 ° C and the second evaporation at 8 ° C. The temperature of the first evaporation allows a strong elimination of the produced hydrolysis flavors,

Furthermore, the strong temperature drop in the extract temperature from greater than 150 ° C to 60 ° C results in a sedimentation of the non-soluble fraction which will then be retained in the intermediate cells. 5 \

The temperature of the second evaporation is considered to be optimal between a satisfactory elimination of undesirable flavors and a minimal reduction of coffee strength.

Thanks to this process, a satisfactory elimination of the organoleptically harmful compounds is thus achieved, avoiding a concomitant reduction of the taste.

In addition, the first evaporation, performed immediately after the warmer cells, causes a decrease in the volume of the filtered extract through the following cells.

This decrease in volume, and therefore the amount of flow, is translated by a decrease in the rate of the extract through the following cells which behave like filters which retain the suspended solids which could have originated from the hot cells.

There follows a decrease in the non-soluble fraction in the final extract.

After all, the two successive evaporations result in a very significant decrease in the amount supplied in the cold extraction cells. This penalizes the weakening which can thus become insufficient within an industrial process.

To avoid this drawback, it is desirable to increase the amount supplied prior to the second evaporation in the cold cells in order to increase the volume of water to come into contact with the coffee to be extracted in said cold cells and thereby increase the weakening. 6

Finally, it is possible to modulate the quality of the final product by adding a more or less considerable amount of water to the outlet of the first evaporation.

This addition of water by increasing the amount supplied in the intermediate cells, and therefore the filtration rate, certainly reduces the decrease of the non-soluble fraction in the final extract, since the filtering effect on the intermediate cells is reduced.

In addition, it is necessary to provide a reheating of the treated liquid extract after each evaporation in order to raise the temperature again to the desired extraction temperature.

A device for carrying out the above-described process is described below.

As shown in the single figure, a coffee extraction device consists of several extraction cells operating in series, each consisting of a column whose lower part is attached to the upper part of the preceding column and whose upper part is attached to the lower part of the following column.

Generally, an extraction device consists of four to eight extraction cells and, preferably, six extraction cells. The cell 1 contains the weakened coffee, while the cell 6 contains the less weakened coffee, decreasing the level of weakening of the cell 1 to the cell 6. The extraction liquid, which may be water under pressure at a temperature comprised 7

between 150 ° C and 180 ° C, enters beneath cell 1, traverses this cell from below upwards absorbing the soluble product, exits the upper part of cell 1 and successively crosses each cell until it crosses cell 6 which is last cell and containing fresh ground roasted coffee.

At the exit from cell 6 the final extract is then obtained which is then filtered and optionally centrifuged, then evaporated, and finally converted into powder by lyophilization or atomization.

In order to carry out the process according to the invention, the extraction cells are divided into a group of hot cells, where the temperature may be higher than 150 ° C, in a group of intermediate cells, where the temperature may be higher 13CTC and in a group of cold cells.

According to preferred embodiment represented in the single figure, the hot cells are cells 1 and 2, the intermediate cells are cells 3 and 4 and the cold cells are cells 5 and 6.

A first U1 intercellular treatment unit is interposed between the hot cell group and the intermediate cell group on the liquid extract circuit.

Likewise, between the intermediate cell group and the cold cell group, a second intercellular treatment unit U2 is interposed.

Each intercellular treatment unit U1, U2 consists of a holding evaporator 7, which comprises a pressure reducing device followed by a flash evaporator. 8 \

At the outlet of the holding evaporator is provided an extraction liquid source 8 which serves to compensate for all or part of the loss of liquid caused by evaporation.

Beneath this source 8 is finally provided a reheater 9 of the treated extract.

The following examples further illustrate the process according to the invention.

Example 1

This example illustrates the influence of the second evaporation performed by the second intercellular treatment unit U2 on the quality of the product obtained.

A series of tests was performed with an extraction device consisting of two warm cells, two intermediate cells and two cold cells. Water was introduced at 180 ° C into the more weakened cell 1, leaving a liquid extract at 172 ° C of cell 2 to be treated by the first intercellular treatment unit U1.

In this unit U1 the instantaneous evaporation temperature was set at 60 ° C.

No liquid was added to the treated liquid extract at the exit of unit U1 and, after reheating at 160 ° C, this liquid extract was reintroduced into cell 3, exiting cell 4 again at 150 ° C.

This liquid extract was then treated in the second U2 intercellular treatment unit and was re-heated to a temperature of 100 ° C to be reintroduced into the cold cell 5.

Four tests were performed at four different evaporation temperatures in unit U2. The results are summarized in the table below,

Flash evaporation temperature in unit U2 (ec) 60 70 80 90

Amount of water evaporated (Kg) per Kg roasted ground coffee 0,31 0,22 0,18 0,11

Amount of added water (Kg) kg Kg roasted ground coffee 1.7 1.6 1, 5 1, 4

There is thus a reduction in the strength of the coffee taste when the evaporation temperature drops with a concomitant increase in the purity of the aroma.

A temperature between 70 ° C and 80 ° C is ultimately preferred as a satisfactory compromise,

Example 2,

This example illustrates the influence of the number of intermediate cells on, on the one hand, the quality of the coffee and, on the other hand, on the non-soluble fraction in the final extract.

In this example, all assays were performed with an extraction liquid entering 180 ° C, then penetrating the first intermediate cell at 140 ° C and the first cold cell at 105 ° C. first evaporation in unit U1 is 60 ° C and the second evaporation temperature in unit U2 is 80 ° C. No liquid was added to the extract after the first U1 unit, while 2 kg of water per kg of Roasted coffee is added to the. output from the second unit U2. 10

The table below summarizes the different tests performed. Number of internal cells 3

Fraction not soluble in final extract (%) 0, 7, 2

Comments Cup very clear * taste very sweet, a little dry. Clear cup, sweet and full palate. Cup cloudy, taste a bit bitter. The optimal choice is therefore to use two intermediate cells. 11

Example 3

This example illustrates the influence of the addition of water after the first evaporation in the UI unit on the ultimate weakening and on the quality of the final product.

All assays were carried out with a second evaporation temperature in unit U2 of 80Â ° C, adding 2 kg of water per kg of roasted coffee following this unit U2, the extraction device comprising two hot cells, two intermediate cells and two cold cells, the yield of weakening being identical in all assays.

Non-soluble fraction (%) 2.1 2.2 2.5

Addition of water after unit U1 (kg of water per kg of roasted ground coffee) 0 1, 5 2,5

An increase in the non-soluble fraction is observed due to the decrease in the filtering effect on the intermediate cells. In addition, the quality of the final product decreases becoming more acrid and harder.

Preferably, therefore, the addition of water after the first evaporation is selected.

But it is clear that this parameter allows modulating the quality of the final product according to the taste to be obtained. 12

Claims (2)

β .............. V ....... I ...... MDIC A ....... Q ....... Q .. A process for the preparation of instant soluble coffee in powder in which an extraction liquid is countercurrently filtered through cells filled with ground roasted coffee, the extract being which is then transformed into powder, characterized in that an extract produced by one or more hot cells is subjected to a first evaporation of the instantaneous type, the produced extract being then reintroduced in the extraction circuit to be subjected to a second evaporation of the instantaneous type separated from the preceding by at least one intermediate extraction cell, the product of this evaporation being then reintroduced into the cold cells of the extraction circuit. 2. A process according to claim 1, characterized in that extraction liquid is added after the second evaporation and before reintroduction into the cold cells. 3. A process according to any one of the preceding claims, characterized in that the first evaporation takes place at 60 ° C and the second evaporation at 80 ° C. 4. A process according to claim 3, wherein the liquid is reheated after each evaporation. dog. A process according to claim 3, characterized in that extraction liquid is added after the first evaporation and before reintroduction into the intermediate cells. The applicant claims the priority of the European patent application filed on 24 October 1990 under the 90120388.5 node. Lisbon, October 23, 1991 14